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102 lines
2.0 KiB
Go
102 lines
2.0 KiB
Go
package lzo
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func (ctx *compressor) initMatch(s *swd, flags uint32) {
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s.ctx = ctx
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s.init()
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if flags&1 != 0 {
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s.UseBestOff = true
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}
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}
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func (ctx *compressor) findMatch(s *swd, thislen uint, skip uint) {
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if skip > 0 {
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if thislen < skip {
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panic("assert: findMatch: invalid thislen")
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}
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s.accept(thislen - skip)
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ctx.textsize += thislen - skip + 1
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} else {
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if thislen > 1 {
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panic("assert: findMatch: invalid thislen")
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}
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ctx.textsize += thislen - skip
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}
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s.MLen = cSWD_THRESHOLD
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s.MOff = 0
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for i := 0; i < len(s.bestPos); i++ {
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s.bestPos[i] = 0
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}
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s.findbest()
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ctx.mlen = int(s.MLen)
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ctx.moff = int(s.MOff)
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s.getbyte()
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if s.BChar < 0 {
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ctx.look = 0
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ctx.mlen = 0
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} else {
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ctx.look = s.Look + 1
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}
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ctx.bp = ctx.ip - int(ctx.look)
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}
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func (ctx *compressor) betterMatch(s *swd, imlen, imoff int) (mlen int, moff int) {
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mlen, moff = imlen, imoff
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if mlen <= m2_MIN_LEN {
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return
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}
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if moff <= m2_MAX_OFFSET {
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return
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}
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if moff > m2_MAX_OFFSET && mlen >= m2_MIN_LEN+1 && mlen <= m2_MAX_LEN+1 &&
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s.BestOff[mlen-1] > 0 && s.BestOff[mlen-1] <= m2_MAX_OFFSET {
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mlen -= 1
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moff = int(s.BestOff[mlen])
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return
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}
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if moff > m3_MAX_OFFSET && mlen >= m4_MAX_LEN+1 && mlen <= m2_MAX_LEN+2 &&
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s.BestOff[mlen-2] > 0 && s.BestOff[mlen-2] <= m2_MAX_OFFSET {
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mlen -= 2
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moff = int(s.BestOff[mlen])
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return
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}
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if moff > m3_MAX_OFFSET && mlen >= m4_MAX_LEN+1 && mlen <= m3_MAX_LEN+1 &&
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s.BestOff[mlen-1] > 0 && s.BestOff[mlen-1] <= m3_MAX_OFFSET {
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mlen -= 1
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moff = int(s.BestOff[mlen])
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return
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}
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return
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}
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func assertMemcmp(b1, b2 []byte, l int) {
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b1 = b1[:l]
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b2 = b2[:l]
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for i := 0; i < len(b1); i++ {
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if b1[i] != b2[i] {
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panic("assertMemcmp: dosn't match")
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}
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}
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}
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func (ctx *compressor) assertMatch(s *swd, mlen, moff int) {
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if mlen < 2 {
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panic("assertMatch: invalid mlen")
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}
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if moff <= ctx.bp {
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if ctx.bp-moff+mlen >= ctx.ip {
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panic("assertMatch: invalid bp")
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}
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assertMemcmp(ctx.in[ctx.bp:], ctx.in[ctx.bp-moff:], mlen)
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} else {
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panic("dict should not exit")
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}
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}
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